Sunday , August 1 2021

16,000 MPH Faster, 2000 Light Years Closer to the Supermassive Black Hole at the Center of the Earth’s Milky Way

Milky Way Galaxy Position and Speed ​​Map

Position and velocity map of the Milky Way Galaxy. Arrows show position and velocity data of 224 objects used to model the Milky Way Galaxy. Solid black lines indicate the positions of the spiral arms of the Galaxy. Colors indicate groups of objects belonging to the same arm. The background is a simulation image. Credit: NAOJ

Earth is only 7 km / h (~ 16,000 mph) faster and approaching supermass about 2000 light years black hole in the center Milky Way Galaxy. But don’t worry, that doesn’t mean our planet is plunging into a black hole. Instead, the changes are the results of a better model of the Milky Way Galaxy based on new observational data, including a catalog of objects observed over a period of more than 15 years by the Japanese radio astronomy project VERA.

VERA (VLBI Exploration of Radio Astrometry, by the way “VLBI” stands for Very Long Basic Interferometer) began mapping three-dimensional velocity and spatial structures in the Milky Way in 2000. VERA uses a technique known as interferometry to combine data from radio telescopes scattered across the Japanese archipelago to achieve the same resolution as a 2300 km diameter telescope. Measurement accuracy The 10 microarcseconds obtained with this resolution is sharp enough, in theory, to dissolve a United States penny placed on the Moon’s surface.

Since the Earth is in the Milky Way Galaxy, we cannot step back and see what the Galaxy looks like from the outside. As an accurate measurement of the positions and movements of objects, astrometry is a vital tool to understand the general structure of the Galaxy and our place within it. This year, the First VERA Astrometry Catalog, containing data on 99 objects, was published.

Based on the VERA Astrometry Catalog and recent observations by other groups, astronomers have created a map of position and velocity. From this map they calculated the center of the Galaxy, the point around which everything revolves. The map shows that the center of the Galaxy and the supermassive black hole located there are 25800 light-years from Earth. This is closer to the official value of 27700 light years, adopted by the International Astronomical Union in 1985. The speed component of the map shows that the Earth is traveling at 227 km / s while orbiting around the Galactic Center. This is faster than the official value of 220 km / h.

Now VERA hopes to observe more objects, particularly close to the central supermassive black hole, to better characterize the structure and motion of the Galaxy. As part of these efforts, VERA will join the EAVN (East Asia VLBI Network), which consists of radio telescopes located in Japan, South Korea and China. EAVN can achieve even higher accuracy by increasing the number of telescopes and the maximum distance between telescopes.

“First VERA Astrometry Catalog” prepared by VERA collaboration and others. It appeared in Japan Astronomical Society Publications in August 2020.

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